The present disclosure relates to fabricating microstructures on a substrate.
Many micro devices include micro structures which are required to have predefined lateral dimensions and heights with specific aspect ratios. For example, a micro mechanical device on a substrate may have a structure portion that protrudes over the substrate. The height of the structure portion over the substrate may vary from several microns to several millimeters. Packaging the micro mechanical device on the substrate may include fabricating a wall structure and a cover. The wall structure can be connected to the substrate and surround the micro mechanical device. The cover is connected to the top surface of the wall structure. The wall structure and the cover can form a chamber on the substrate. To encapsulate the micro mechanical device in the chamber, the wall structure needs to be higher than the micro mechanical device on the substrate. The wall structure may be required to be as high as several hundred microns to several millimeters. The wall structure is often required to be separated from the micro mechanical device by a well defined distance within the chamber to ensure the proper operation of the micro mechanical device and to minimize the footprint of the micro mechanical device and the chamber on the substrate. The lateral dimensions of the wall structure thus often need to be minimized and controlled within a small tolerance.